Project Summary and Abstract The overall goal of this proposal is to support the training of Dr. Byron Lee to become an independent investigator conducting translational research in bladder cancer epigenomics. Dr. Lee will be mentored by Dr. Nima Sharifi and Dr. Peter Scacheri. Dr. Nima Sharifi is the leader of the Genitourinary Malignancies Program at the Case Comprehensive Cancer Center and has mentored numerous young physician-scientists. Dr. Peter Scacheri is Professor of Genetics at Case Western Reserve University and an expert in cancer epigenomics. The training plan incorporates the following goals: (1) enhance understanding of chromatin biology, (2) gain expertise in bioinformatics analysis of complex biological data, and (3) develop proficiency in the use of patient-derived samples for translational research. Bladder cancer is the fifth most common non-cutaneous malignancy in the United States, yet few new treatment options exist. The Cancer Genome Atlas (TCGA), a large-scale effort supported by NCI and NHGRI to determine the molecular basis of cancer, performed comprehensive molecular characterization of over 400 muscle invasive bladder cancers and showed that chromatin modifier gene alterations occur in 75% of cases. Most of these alterations are predicted to result in loss of function; however, their effects on bladder cancer initiation, progression, and response to therapy are largely unknown. These genes alter the configuration of the DNA-histone interface, which affects the ability of DNA-binding proteins to access their target sequences. The central hypothesis that will be tested is that chromatin modifier gene mutation leads to gene expression changes that support bladder cancer initiation and progression through enhancer disruption. To accomplish this goal, we propose the following Specific Aims: (1) Test the hypothesis that KDM6A inactivation alters the chromatin state of urothelial cells and engenders a transcriptional program that results in neoplastic growth, and (2) Test the hypothesis that enhancer dysfunction and aberrant transcriptional circuits characterize human bladder cancer and dependence on these circuits for growth result in vulnerability to existing targeted therapies. Successful completion of the proposed research will advance our understanding of how chromatin modifier gene mutations, one of the most frequent somatic alterations in bladder cancer, affect disease initiation and progression. Moreover, we expect to identify molecular vulnerabilities arising from enhancer disruption and changes in transcription factor circuits. Targeting these vulnerabilities can lead to the development of novel therapies for bladder cancer.